One of the methods of donor heart protection against
ischemia is a substantial lowering of temperature of the heart perfused with
cardioplegic solution (CS). The achieved conservation of energetically rich compounds, however, does not guarantee the full restoration of heart function during reperfusion. Another possibility for heart preservation is repeated application of CS at 20 degrees C. This variant was tested in our experiments on isolated rat hearts perfused under constant pressure with the
Krebs-Henseleit solution according to Langendorff. During global
ischemia (180 min at 20 degrees C) we applied the St. Thomas Hospital CS lx or 4 x at 60 min intervals. During the
ischemia,
glycogen,
ATP,
lactate, Na+, K+ were assessed in the heart. The
heart injury was monitored as the release of
lactate dehydrogenase (LD) during the 60 min reperfusion. Repeated CS perfusion of the heart during
ischemia lowers the contents of
lactate and maintains
ATP and
glycogen content at elevated levels throughout
ischemia. The improved condition of the heart after repeated CS application demonstrated as prevention of the gain of Na+ in the cells at the end of
ischemia as well as after reperfusion. This was associated with reduced intracellular
potassium depletion and LD release into the perfusate.